Reproductive system

Reprocessing Reproductive physiology Reproductive system Reprographic inks Reprography Re-refining... 

Exposure to excessive amounts of lead over a long period of time (chronic exposure) increases the risk of developing certain diseases. The parts of the body which may be affected include the blood, nervous system, digestive system, reproductive system, and kidneys. These effects include anemia, muscular weakness, kidney damage, and reproductive effects, such as reduced fertiHty in both men and women, and damage to the fetus of exposed pregnant women. 

In addition to the weU-defined opioid systems in the central nervous system, the three opioid peptides and their precursor mRNA have also been identified in peripheral tissues. ( -Endorphin is most abundant in the pituitary, where it exists in corticotroph cells with ACTH in the anterior lobe and in melanotroph cells with MSH in the intermediate lobe (59). Enkephalin and pre-pro-enkephalin mRNA have been identified in the adrenal medulla (60) and this has been the source of material for many studies of pro-enkephalin synthesis and regulation. Pre-pro-enkephalin mRNA has also been identified in the anterior and posterior lobes of the pituitary (61). mRNA for all three opioid precursors has been identified in the reproductive system (62—64). POMC... 

Reproductive System. The primary PGs are intimately involved in reproductive physiology (67). PGE2 and PGP2Q, are potent contractors of the pregnant utems and intravenous infusion of either of these compounds to pregnant humans produces a dose-dependent increase in frequency and force of uterine contraction. PGI2 and TXA2 have mild relaxant and stimulatory effects, respectively, on uterine tissue. The primary PGs also play a role in parturition, ovulation, luteolysis, and lactation and have been impHcated in male infertility. 

Finally, a new class of antispermatogenic agents containing the same fundamental structure cited above has been described (76JMC778). 1-Halobenzyl-l J/-indazole-3-carboxylic acids are potentially useful for birth control, and because they act after a single administration they are of interest for the physiological study of the male reproductive system. 

In order to fully appreciate the potential implications of endocrine disruption, it is important to consider the normal role of hormones in controlling the development and functioning of the reproductive systems of the different vertebrate classes. 

In addition to their endocrine disrupting properties, it must be appreciated that many of the chemicals in question possess more general toxic properties, which may be potentiated by metabolism by the organism. Several PAHs, PCBs and PCDDs are carcinogenic, while certain phthalate esters can enhance the excretion of zinc, potentially leading to zinc deficiency. Zinc, an essential element, plays a vital role in spermatogenesis and mature T-cell production. Deficiency may result in abnormalities of the male reproductive system, depletion of spermatogenesis and suppression of the immune system. 

Effects of Oestrogen on the Development and Function of the Male Reproductive System... 

It needs to be noted that a toxic effect on the reproductive system may be mediated through alterations in normal functions of the central nervous system, gonads (ovaries, testicles), or on the pharmacokinetics of reproductive hormones. ... 

TABLE 5.17 Examples of Chemical Compounds that Affect the Reproductive System... 

Thomas, J. A. (1996). Toxic responses of the reproductive system. In Casarett and Doull s Toxicology The Basic Science of Poisons (C. D. Klaassen, Ed.), pp. 547-581. McGraw-Hill, New York. 

If xylene and toluene both affect the huintui reproduction system in response to clu onic exposure, what is tlie liazard index response exposure level for toluene is 200 pg/m. ... 

As to be expected from a peptide that has been highly conserved during evolution, NPY has many effects, e.g. in the central and peripheral nervous system, in the cardiovascular, metabolic and reproductive system. Central effects include a potent stimulation of food intake and appetite control [2], anxiolytic effects, anti-seizure activity and various forms of neuroendocrine modulation. In the central and peripheral nervous system NPY receptors (mostly Y2 subtype) mediate prejunctional inhibition of neurotransmitter release. In the periphery NPY is a potent direct vasoconstrictor, and it potentiates vasoconstriction by other agents (mostly via Yi receptors) despite reductions of renal blood flow, NPY enhances diuresis and natriuresis. NPY can inhibit pancreatic insulin release and inhibit lipolysis in adipocytes. It also can regulate gut motility and gastrointestinal and renal epithelial secretion. 

Recently, leaders in the pharmaceutical industry have developed a list of desired properties for a fourth generation of SERMs (Table 2). In general, future SERMs must oppose endogenous hormone action in the breast and reproductive system while displaying full estrogenic effects in the cardiovasculature, bone and central nervous systems. Additional criteria are that fourth generation compounds possess superior bioavailability compared with existing SERMs and have... 

Estrogens mainly affect the growth and maturation of the female reproductive system and the maintenance... 

The estrogens are secreted by the ovarian follicle and in smaller amounts by the adrenal cortex. Estrogens are important in the development and maintenance of the female reproductive system and the primary and secondary sex characteristics. At puberty, they promote growth and development of the vagina, uterus, fallopian tubes, and breasts. They also affect the release of pituitary gonadotropins (see Chap. 50). 

Reproductive Toxicity—The occurrence of adverse effects on the reproductive system that may result from exposure to a chemical. The toxicity may be directed to the reproductive organs and/or the related endocrine system. The manifestation of such toxicity may be noted as alterations in sexual behavior, fertility, pregnancy outcomes, or modifications in other functions that are dependent on the integrity of this system. 

---